TERRY O'GORMAN: Oh this is a major decision. This case overturned generations, indeed hundreds of years of legal understanding on that point.

ASHLEY HALL: The Council of Civil Liberties president, Terry O'Gorman says the consequences will reverberate throughout Australia.

TERRY O'GORMAN: The effects of this is that whatever passes between a husband and wife in their marriage, they can be compelled, against their wishes, to give evidence against the other in criminal proceedings in any court across the land.

ASHLEY HALL: And Mr O'Gorman says it won't just be in criminal circles where the impact is felt.

TERRY O'GORMAN: The historical justification for the rule has been that if a husband is compelled to give evidence against his wife, or vice versa, that puts strains on the institution of marriage.

ASHLEY HALL: The case began in 2009, when Louise Stoddart was forced to appear before the Australian Crime Commission to answer questions about the alleged tax fraud of her husband Ewan Alisdair James Stoddart.

Ms Stoddart refused and she went to the Federal Court seeking an injunction to stop the commission from asking any more questions.

At first, the Federal Court sided with the commission.

On appeal, it found that Ms Stoddart was indeed protected by what's known spousal privilege.

But the High Court today disagreed.

JEREMY GANS: The issue that had been thought would be discussed by the High Court today was whether this act governing the Australian Crime Commission, which abolished the privilege against self-incrimination, also abolished the privilege against spousal incrimination.

ASHLEY HALL: Jeremy Gans is an Associate Professor at the University of Melbourne's Law School.

JEREMY GANS: But the High Court, or five judges of the High Court, never got to that issue because they decided there had never been a privilege against spousal incrimination in the first place.

ASHLEY HALL: Does that surprise you?

JEREMY GANS: No. It was never a certain thing that there was such a privilege. It had been widely talked about and there was a case from the early 19th century that seemed to give it some credence and it's been picked up by textbook writers and others ever since but there simply hasn't been a lot of law on it for the last 200 years.

ASHLEY HALL: Professor Gans says the ruling is out of step with the common law of many other countries with similar legal systems.

JEREMY GANS: If we were any other country in the world, if we were Canada or the United States or the UK, the argument in the court would have been about matters of high policy, whether it's right - it's a good thing that spouses can be forced to incriminate their partners, whether it's a appropriate that such a privilege only applies to married people as opposed to all family members, whether a statute that abolishes the right against incriminating yourself should also be seen as abolishing the right against incriminating your spouse.

All those are really fascinating questions but I don't think this question of how the common law developed is all that interesting a question compared to those.

He's also worked in Victoria's Office of the Chief Examiner, which has similar powers to coerce witnesses to give evidence as the Crime Commission.*

ADAM CHERNOK: I particularly like the minority judgement of Justice Heydon. His Honour finds that the privilege does actually exist and he says that, and I'm quoting here, "it preserves a small area of privacy and immunity from the great intrusive powers of the state and those who invoke them. It fosters human dignity, it helps maintain self-respect." I think that sort of language is the appropriate language in a sense.

ASHLEY HALL: But that was the dissenting judgement.

ADAM CHERNOK: Yes

ASHLEY HALL: So it may pave the way for a reversal sometime well down the track but at this point it is the minority decision.

ADAM CHERNOK: Yes, absolutely, absolutely.

ASHLEY HALL: Neither Ms Stoddart, nor her solicitor would speak to PM about the case, as they're still absorbing the judgement.

Likewise, no-one from the Crime Commission would speak, except to say that they're also considering the judgement.

But Mr Chernok says the decision will make the commission's work easier.

ADAM CHERNOK: I personally have real concerns about the use of coercive powers in the context of standing commissions, as opposed to royal commissions; and royal commissions bring with them their own issues, in terms of using these coercive powers. But I just think that in the context of having them on an ongoing basis in the same way that the ACC does really can lead to essentially abuses of that power.

ASHLEY HALL: So I guess we should think twice about sharing secrets with our spouse now?

ADAM CHERNOK: Absolutely, absolutely. And that should always be the position anyway. In legal terms if you (laughs), if you're concerned that you're going to be called before the Australian Crime Commission then loose lips sink ships as they say and you don't necessarily want to put your spouse in a position where they may have to give evidence against you and certainly this judgement really reinforces that.